Engine "wobble" or "strain" in park

tyler durdz

Member
Joined
May 27, 2017
Messages
11
Reaction score
1
Your Mercedes
A200/2014/1.8d/AMG LINE
Hi guys and gals

I have an a200 2014 7G-DCT, and when I start the car in park (cold or warm) the engine sounds like it wants to pull away - as if it was in drive and there was a strain (I'm pretty sure the car isn't trying to move). It almost sounds like a soft knock or wobble. If I click the gear button and pop it into neutral, the noise immediately dies away, and if i pop it back into park the noise is gone.

Its on 7k miles and last had an A service at 5.8k miles.

Does anyone have any idea what it could be?
 

Submariner1

Senior Member
Joined
Sep 3, 2016
Messages
4,689
Reaction score
787
Location
Windsor Berkshire
Your Mercedes
CL500 2009 5.5
Hi guys and gals

I have an a200 2014 7G-DCT, and when I start the car in park (cold or warm) the engine sounds like it wants to pull away - as if it was in drive and there was a strain (I'm pretty sure the car isn't trying to move). It almost sounds like a soft knock or wobble. If I click the gear button and pop it into neutral, the noise immediately dies away, and if i pop it back into park the noise is gone.

Its on 7k miles and last had an A service at 5.8k miles.

Does anyone have any idea what it could be?
Get to a main dealer fast and make thrm fix it under warranty, even if you are a few months out. Kick up a stink at 7,000 miles.
 

Botus

Senior Member
Joined
Jul 29, 2014
Messages
6,287
Reaction score
2,475
Location
UK
Your Mercedes
S500/2010/500
I'd want to understand what it is you are trying to say the car is allegedly doing

I have no real idea what it is you are trying to explain.
Are you saying it "now" appears to idle more slowly than it was...
what speed does the rev counter say its doing? and if its slower how much and how long ago
have u turned on the AC due to warm weather and are noticing the engine wiorking fractionally harder or the condenser cooling fan is now running ?
 
OP
T

tyler durdz

Member
Joined
May 27, 2017
Messages
11
Reaction score
1
Your Mercedes
A200/2014/1.8d/AMG LINE
  • Thread Starter
  • Thread starter
  • #4
I'd want to understand what it is you are trying to say the car is allegedly doing

I have no real idea what it is you are trying to explain.
Are you saying it "now" appears to idle more slowly than it was...
what speed does the rev counter say its doing? and if its slower how much and how long ago
have u turned on the AC due to warm weather and are noticing the engine wiorking fractionally harder or the condenser cooling fan is now running ?

Hi, I've tried to do some research on this and now i think there might be another problem. I will try to explain the best i can.

Firstly, with a DCT-Auto, if the car is in drive and you come to a stop and continue holding the brake, should the car still try to move forwards? or does the transmission get disengaged? At the moment the car sounds like it is trying to move forward. It is sort of a low rumble engine strain noise. If i let go of the the brake the noise disappears, or if i pop it into park or neutral the noise also disappears. But if i put it back into drive (again with my foot firmly on the brake so i don't move away) the noise returns. Is this normal?

Sometimes (not all the time) when i turn the car on in park, I get the same noise - a low rumble engine strain noise as if the car was trying to pull away, but since my foot isn't on the brake, I'm certain the car isn't trying to move away. If i rev the engine (still in park) the noise gets louder. If i put the car in neutral the noise completely disappears. If i put it in park again there is no noise.
The engine idles at around 800-900. The idling speed is constant throughout this process.

Does that make sense?
 

Botus

Senior Member
Joined
Jul 29, 2014
Messages
6,287
Reaction score
2,475
Location
UK
Your Mercedes
S500/2010/500
Firstly, with a DCT-Auto, if the car is in drive and you come to a stop and continue holding the brake, should the car still try to move forwards? or does the transmission get disengaged? At the moment the car sounds like it is trying to move forward. It is sort of a low rumble engine strain noise. If i let go of the the brake the noise disappears, or if i pop it into park or neutral the noise also disappears. But if i put it back into drive (again with my foot firmly on the brake so i don't move away) the noise returns. Is this normal?

No, not normal.

Should be zero drive with brake applied when stationary, but creep when you lift off brakes is normal, so you might think its always been driving when you lift off the brake.

Many DTC's have a system to recalibrate the dual clutch set up. Will vary on who does it and how to do it. Read the manual and if unclear go to Dealer. I'd try another car of same type to see if its different to yours

The noise could be exhaust or heat shield that's loose or in the wrong place and not necessarily engine / gearbox related. If you blip throttle in park and turn on / off the AC can you get similar noise?
 
OP
T

tyler durdz

Member
Joined
May 27, 2017
Messages
11
Reaction score
1
Your Mercedes
A200/2014/1.8d/AMG LINE
  • Thread Starter
  • Thread starter
  • #6
No, not normal.

Should be zero drive with brake applied when stationary, but creep when you lift off brakes is normal, so you might think its always been driving when you lift off the brake.

Many DTC's have a system to recalibrate the dual clutch set up. Will vary on who does it and how to do it. Read the manual and if unclear go to Dealer. I'd try another car of same type to see if its different to yours

The noise could be exhaust or heat shield that's loose or in the wrong place and not necessarily engine / gearbox related. If you blip throttle in park and turn on / off the AC can you get similar noise?

So should the transmission disengage when the car is stopped and the brake is firmly pressed? I'll go and take a video of the symptoms now and post it.

When in park, the noise doesn't happen when blipping the throttle. Ill go and try the AC now.

Thanks
 
OP
T

tyler durdz

Member
Joined
May 27, 2017
Messages
11
Reaction score
1
Your Mercedes
A200/2014/1.8d/AMG LINE
  • Thread Starter
  • Thread starter
  • #7
update: The AC has no effect on the noise, neither does blipping the engine.
When its in D or R, with the foot brake firmly on, if I let go of the brake there is a very small delay before the car moves away so I'm starting to think that it may not be trying to move away, but rather the engine or transmission is vibrating under some load.
If this was the case, maybe it could be an engine/transmission mount issue? However this seems odd as the idle speed remains the same whether in P, D or R.
 
OP
T

tyler durdz

Member
Joined
May 27, 2017
Messages
11
Reaction score
1
Your Mercedes
A200/2014/1.8d/AMG LINE
  • Thread Starter
  • Thread starter
  • #8
update: I have managed to figure out when the park noise problem occurs. These are the steps:
  1. Get the car on an incline facing forwards in D
  2. Put the car in P
  3. Turn off the engine without applying the parking brake
  4. The car then rolls back slightly then stops (because of the parking gear i assume?)
  5. Put the parking brake on
  6. Turn the car on
  7. The engine now vibrates ( a low rumble as if it was trying to pull off)
  8. Put the car in N and the noise is gone
  9. Put the car in P and the noise remains gone.
I repeated this process 3 times to see if it was definitely the cause and it happened every time (I don't want to do it again just in case I'm wearing something out). If i change step 3. to include putting the parking brake on before turning off the engine, the noise doesn't happen when i turn the car back on, so i assume it has something to do with the car rolling back before the parking brake catches?

Could someone try this with their DCT-7g and see if they can replicate the problem?
 

John Laidlaw

Senior Member
Joined
Nov 15, 2013
Messages
26,373
Reaction score
9,163
Location
Wirral
Your Mercedes
Land Rover Discovery 4
Something happening with the pawl possibly? That's what you're seeing on 4. Certainly.
 

Botus

Senior Member
Joined
Jul 29, 2014
Messages
6,287
Reaction score
2,475
Location
UK
Your Mercedes
S500/2010/500
I should have thought of this before.... it would explain things quite nicely !!!

I don't know how a DTC has "park". Not sure why they'd bother with an "auto gearbox parking pawl" it would cost money and they could do it another way.

You could lift both of the clutches (hence engage e.g. foot on the clutch) to get neutral !!! BUT leave both gearboxes in a gear. That locks things up so it won't roll anywhere, but you'd have a bit of slop in the drive train, which could be why it moves a bit.

If that's the case and both your clutches are not set up optimally your car could be very lightly slipping the clutch (wearing things out, dragging the revs down and making it work for a living)

hence my first post about..

"Many DTC's have a system to recalibrate the dual clutch set up. Will vary on who does it and how to do it. Read the manual and if unclear go to Dealer. "

Trying another car will help identify if yours in not std. (now you know how to make yours do it).
 
Last edited:

Peter Au

New Registration
Joined
Nov 9, 2022
Messages
1
Reaction score
0
Your Mercedes
CLA 220D
Hello just wondering if you ever got this fixed my cla dose the same thing mercedes have checked it a few times it's had extra transmission services done, and they said it is from putting it in hold before pressing park, and the tec said they are a super strong gearbox and it won't hurt it anyway but i don't like it especially when you start the car and there is load on the engine. but that was just a theory it still dose it, but not all the time so it is hard to get it identified by the tec and im not close to a mercedes dealer lol 1000km away. There is load on the engine when you press park even on flat ground if you move from park to neutral it stops most of the time, my thoughts are that there is a pressure dump solidnoid or valve in the valve body sticking that keeps clutch pressure up a bit but it should be in neutral as well so what is it loaded against, the park paw is only loaded if you roll the car in neutral onto the paw lock. Anyway if you got it sorted or know someone that has the smarts to identify the cause I would appreciate the help. Thanks peter
 

d:class automotive are specialists in automotive interiors and upholstery. From Mercedes and modern cars to custom and classics. Tel: 01483 722923 Email:info@dclass.co.ukWeb:www.dclass.co.uk
Top Bottom